摘要:

Summary.Three hundred and forty eight strains of micro‐organisms were isolated from packaged bacon which had been cured by one or other of 2 methods (A and B) and stored at 0–10° for 7 weeks. Before storage,Micrococcussub‐group 7 (47%) and coryneform bacteria (33%) were the principal contaminants of bacon cured by method A andMicrococcussubgroup 1 (20%) andMicrobacterium thermosphactum(21%), in bacon cured by method B. After 7 days at 0°, coagulase negative staphylococci accounted for 10 and 33% of the microflora in bacon A and B, respectively: other organisms were micrococci, 60% (A) and 25% (B); corynebacteria, 20% (A) and 12·5% (B), yeasts (Torulopsis candidaandT. dattila) 5% (A) and 29% (B). In the following month at 10°,Micrococcussub‐group 5 was the dominant (43–88%) contaminant of bacon B; the incidence ofStreptococcusGroup N ranged from 27–36% and that of unidentified lactic acid bacteria from 23–32%. Towards the end of storage, the order of dominance wasMicrococcussub‐group 3 (38–58%) and atypical streptobacteria (38%) in A;StreptococcusGroup N (42%) and Gram positive rods (5–20%) in B. Staphylococci tended to die out during storage of bacons cured by the 2 methods and coagulase positive staphylo

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1973.tb04140.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary.During growth ofClostridium sporogenesin tryptone‐salt‐peptone‐glucose medium the pH value of the medium varies due to formation of acid and CO2and to subsequent production of NH3. Glucose concentrations of 0·2, 0·5 or 1·0% result in increasing sporulation times and in spores of low, extremely high (D110c. 80 min) and negligible heat resistance, respectively. When the pH value is maintained at 7, a reproducible sporulation time of a few hours is observed and the resulting spores have a heat resistance (D110) of 13 min, regardless of the glucose conce

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1973.tb04141.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary.In a study of the origin of the initial microflora of palm wine from the oil palm (Elaeis guineensis), micro‐organisms from parts of the immature spadix, the plant tissues around the point of tapping the tree, the palm leaves and the atmosphere around the palm trees, were isolated and examined. It was shown that the yeasts in fresh palm wine might have originated from those that colonize those parts of the palm which are covered with fluffy hairy outgrowths. These materials which surround the tapping hole are the stalk of the male inflorescence, the leaf petiole, the felt (a fabric‐like outgrowth of the frond petiole used to cover the tapping hole) and the cross strips. Another possible source of the yeasts was the xylem str

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1973.tb04142.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary.UV light was used to induce mutations in 4 strains ofRhizobium trifolii.Mutations were found with modified acid production, generation time, polysaccharide production and symbiotic effectiveness on S184 white clover. Of 72 mutants examined, one was more effective than the parent, 9 had either similar or reduced effectiveness compared with their parental strains and the remainder were non‐infective. A significant correlation (P<0·05) was found between the effectiveness of the strains and their acid production on an agar medium but no such relationship was found in liquid medium. No other relationships were found between any of the physiological or symbiotic characteristics examin

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1973.tb04143.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary.The presence ofStreptococcus zymogenesin samples plated for the enumeration ofClostridium perfringensmarkedly reduces the numbers of clostridial colonies. This effect is not overcome by the use of media usually recommended for the selective isolation ofCl. perfringens, but an agar medium containing 100 μg of both D‐cycloserine and neomycin/ml proved satisfactory. Use of this medium for estimating numbers ofCl. perfringensin the gut of gnotobiotic quail has shown that inhibition byStrep. zymogenedoes not appear to occurin vi

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1973.tb04144.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary.Bacteria were isolated from raw and pasteurized milks produced throughout S. E. Queensland. Milk samples were plated initially on penicillin agar or on milk agar and incubated at 30° and 7°, respectively. On the basis of primary characterization, 167 of the 330 isolates obtained were identified asPseudomonasspp. The pseudomonads were further characterized in accordance with the taxonomic studies of the genus by Stanier, Palleroni&Doudoroff (1966). Species designations were ascribed to thePseudomonasisolates on the basis of distinctive species characteristics in conjunction with similarity coefficients between each isolate and the ideal species phenotype, as follows:Ps. fluorescens(121),Ps. aeruginosa(16),Ps. putida(12),Ps. maltophilia(9),Ps. pseudoalcaligenes(5),Ps. cepacia(3) andPs. alcaligenes(1). A dendrogram obtained by cluster analysis of thePseudomonasisolates is include

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1973.tb04145.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary.When plated on mineral synthetic media with D‐fructose as a sole carbon and energy source 7 strains of actinomycetes belonging to different streptomycete species regularly produced secondary variant colonies in high yield. Beside the ability of strepto‐mycetes to utilize fructose as a sole carbon source, the following factors were shown to be of importance in the control of variational events: the state of the parent culture used for platings; the composition of fructose‐containing media used for the production of variants. Indole, anthranilate and phenol inhibited formation of secondary colonies by most strains. Phenotypically all the variants obtained shared in common the loss of ability to form secondary (aerial) mycelium and spores as well as a tendency of the substrate mycelium to fragment. These traits were shown to be: hereditarily stable on all media tested for variants derived fromStreptcmyces ruber, Str. roseolus, Str. lateritiusandStr. roseoflavusvar.roseofungini;less stable and nutritionally affected for variants derived fromStr. albocyaneus, Str. roseoflavusandStr. anthocyaneus;unstable on all except fructose‐containing mineral medium for the variants ofStr. flavofungini.Vegetative growth of some of the variants obtained was not inferior to that of parent cultures; some variants produced increased amounts of intracellular antibiotics. Some implications of the reported findings are di

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1973.tb04146.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary.A significantly higher number of coliform and faecal coliform organisms were isolated using lactose‐glutamic acid medium than by using lauryl sulphate‐tryptone, lactose, brilliant green‐bile or EE broths. With brilliant green‐bile and lauryl sulphate‐tryptone broth, coliforms/Enterobacteriaceae were isolated less often than with the others. For the detection of faecal coliforms, EE broth proved less good than all other media. All 5 media showed more coliforms/Enterobacteriaceae after 48 h than after 24 h at 30°. Few false positive results were obtained using any of t

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1973.tb04147.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary.The changes in electrode potential recorded by a platinum foil electrode, and in pH, during the incubation ofClostridium butyricumspores in a medium continuously sparged with a sterile gas mixture have been correlated with the biological events occurring simultaneously. The marked fall inEhwhich occurs during incubation is recorded by this type of electrode as occurring during the period of rapid cell replication; this observation may be an artefact associated with foil electrodes and the authors feel that results obtained with such electrodes should be interpreted with caution. The stimulating effect of CO2and the increasingly inhibitory effect on germination of O2, as the concentration of the latter in the gas mixture is increased, have been noted. The inhibitory effect is thought to be due to the O2itself and not to the highEhproduced in the medium by the O2.

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1973.tb04148.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary.The bactericidal activity of long chain saturated fatty acids was antagonized by alkaline earth metals. The activity of linoleic acid was less effectively antagonized but was more sensitive to reversal by ferric and stannous ions. With increasing pH value the bactericidal activity of lauric acid decreased but that of the longer chain saturated acids increased. Both Gram positive and Gram negative bacteria reversibly adsorbed fatty acids. Uptake increased with decreasing pH value and increasing chain length. Although adsorbed to a lesser extent, the intrinsic activity of linoleic acid was greater than lauric acid. The uptake appeared to be non‐specific and governed by the physicochemical properties of both the acids and the bacterial cell surfaces. Sensitivity to the fatty acids increased with decreasing pH value. Protoplasts ofBacillus megateriumadsorbed fatty acids to a greater extent than whole cells. Resistance of the Gram negativePseudomonas phaseolicolawas not due to non‐adsorption of the fatty ac

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1973.tb04149.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY